The effects of Arochlor-1254 induction on the levels of rat hepatic enzymes, and on the ability of induced liver preparations to metabolize benzo(a)pyrene (BaP) and 2-aminoanthracine (2-AA) to mutagens was studied. Arochlor treatment induced cytochrome P488/450, arylhydrocarbon hydroxylase (AHH), aniline hydroxylase, aminopyrine N-demethylase and DMN-N-demethylase in both Sprague-Dawley and Fisher-344 rats. Arochlor treatment enhanced the mutagenicity of BaP for Salmonella typhimurium TA-98 but depressed the mutagenicity of 2-AA. Freezing and storage of the liver preparations affected neither enzymic activity nor metabolic activation of BaP or 2-AA.